Create WebP Images

WebP is an image file format from
Google that provides lossy compression (like JPEG) as well as transparency (like
PNG) but can provide better compression than either JPEG or PNG. Lossy WebP
images are supported in Android 4.0 (API level 14) and higher, and lossless and
transparent WebP images are supported in Android 4.3 (API level 18) and higher.
This page shows how to convert images to WebP format and how to convert WebP
images to PNG format.

Note: Because support for lossless and transparent WebP
images is only available in Android 4.3 and higher, your
project must declare a minSdkVersion of 18 or higher to create
lossless or transparent WebP images using Android Studio.

For more information about the WebP image format, see the WebP
site. For more information about
selecting the correct image format to improve download speed, see Reduce Image
Download
Sizes.

Convert images to WebP

Android Studio can convert PNG, JPG, BMP, or static GIF images to WebP format.
You can convert individual images or folders of images. To convert an image or
folder of images, proceed as follows:

Right click on an image file or a folder containing a number of images
files, and then click Convert to WebP.

The Converting Images to WebP dialog opens. The default settings
depend on the minSdkVersion setting for the current module.

Figure 1. The Converting Images to WebP dialog

Select either lossy or lossless encoding. Lossless encoding is
only available if your minSdkVersion is set to 18 or higher.
If you select lossy encoding, set the encoding quality, and choose whether
or not to view a preview of each converted image before saving.

You can also choose to skip converting any files where the encoded
version would be larger than the original, or any files with transparency
or an alpha channel. Because Android Studio only allows you to
create transparent WebP images if your minSdkVersion is set
to 18 or higher, the Skip images with transparency/alpha channel
checkbox is automatically selected if your minSdkVersion
is lower than 18.

Click OK to begin the conversion. If you are converting more than
one image, the conversion is a single step, and can be undone to revert all
the images you converted at once.

If you selected lossless conversion above, the conversion happens
immediately. Your images are converted in place in their original
location. If you selected lossy conversion, continue on to the next step.

If you selected lossy conversion, and you chose to
view a preview of each converted image before saving, Android Studio
shows you each image during the conversion so you can inspect the
conversion result. (If you did not choose to view a preview, Android
Studio skips this step, and converts your images immediately.) During
the preview step, you can adjust the quality setting for each image
individually, as described below.

Figure 2. Converting a JPG to WebP format at 75% quality

Figure 2 shows the original JPG image on the left and the lossy encoded
WebP image on the right. The dialog shows the file size for the original
and the converted image. You can drag the slider left or right
to change the quality setting and immediately see the effect on the
encoded image and the file size.

The middle area shows the pixels that differ between the original
and the encoded image. In figure 2, with the quality set to 75%, there's
almost no difference between the two images. Figure 3 shows the same image
encoded with the quality set to 0%.

Figure 3. Converting a JPG to WebP format at 0% quality

Note: If you set the quality to 100% and the
minSdkVersion is set to 18 or higher, Android Studio
automatically switches to lossless encoding instead.

Select a quality setting for each image you review. If you are converting
more than one image, click Next to advance to the next image.

Click Finish. Your images are converted in place in their original
location.

Convert WebP images to PNG

If you want to use a WebP image from your project for another purpose (for
example, in a web page that needs to correctly display images in a browser
without WebP support), you can use Android Studio to convert WebP images to PNG
format. To convert a WebP image to PNG, proceed as follows:

Right click on a WebP image in the Android Studio, then click Convert to
PNG.

A dialog appears, asking if you would like to convert the image to PNG,
deleting the original WebP file, or keep the original WebP file as well as
the new PNG file. Click Yes to delete the original WebP file, or No
to retain the WebP file in addition to the PNG file. Your image is converted
immediately.